Toshiro Mifune stars as Isaburo Sasahara, an aging swordsman living a quiet life until his clan lord orders that his son marry the lord's mistress, who has recently displeased the ruler. Reluctantly, father and son take the woman in, and, to the family’s surprise, the young couple fall in love. But the lord soon reverses his decision and demands the mistress’s return. Against all expectations, Isaburo and his son refuse, risking the destruction of their entire family.